Scissors-type lifting linkage elevator

ABSTRACT

An elevator, for example, a commercial aircraft cargo loading elevator, utilizing a scissors-type lifting linkage, wherein the variation of the lifting force required by the lifting actuator means is minimized during the entire lifting cycle by utilizing scissors-type linkage pivot means offset below the planes formed by the two frames and attaching the lifting means above the plane of one of said frames. The use of such offset center pivot means in combination with said scissors-type linkage permits a scissors linkage geometry with minimum variation in lifting actuator force during the entire lifting cycle, and with such a structure a controlled platform translation in the direction transverse to the lifting direction is accomplished.

United States Patent inventors lhakon G. Egeland 7 SeIbrook Lane,Stoneybrook, N.Y. 11790;

John Dioguardi, 16 Sandy Court, Port Washington, N.Y. 11050 July 28,1969 Dec. 21 l 97 l Continuation-impart of application Ser. No. 646,393,June 15, 1967, now abandoned. This application July 28, 1969, Ser. No.20,443

Appl. No. Filed Patented SCISSORS-TYPE Lil-TING LINKAGE ELEVATOR 5Claims, 5 Drawing Figs.

US. Cl 254/122, 187/18 lnt.Cl. B661 3/22, B66b ll/04 Field of Search254/122,

Primary Examiner-Othell M. Simpson Attorney-John P. Chandler ABSTRACT:An elevator, for example, a commercial aircraft cargo loading elevator,utilizing a scissors-type lifting linkage, wherein the variation of thelifting force required by the lifting actuator means is minimized duringthe entire lifting cycle by utilizing scissors-type linkage pivot meansoffset below the planes formed by the two frames and attaching thelifting means above the plane of one of said frames. The use of suchoffset center pivot means in combination with said scissorstype linkagepermits a scissors linkage geometry with minimum variation in liftingactuator force during the entire lifting cycle, and with such astructure a controlled platform translation in the direction transverseto the lifting direction is accomplished.

PATENTED naczl m SHEET 1 [1F 2 INVENTORJ 14:0 :0 5 f 2/00 John Olayam/U,- Br 64/ ATTORNEY SCISSORS-TYPE LIFIING EINKAGE ELEVATOR Thisapplication is a continuation-in-part of our application Ser. No.643,393, filed June IS, 1967 now abandoned.

This invention relates to elevators utilizing a scissors-type liftinglinkage for lifting various types of aircraft cargo loads, with ahydraulic lifting and lowering means, wherein there is a load platformattached to said lifting linkage, and said platform and saidscissors-type lifting linkage are at all times efficiently raised by theactuator means from their package from initial lift-off to the finalheight with a minimum variation in lifting actuating force or, in otherwords, with the actuating load on the actuatorbeing as constant aspossible and accompanying simultaneous controlled platform translationin the direction transverse to the lifting direction.

Scissors-type linkage elevators are generally known and have beendisclosed in such US. patents as the McCartney et al. US. Pat.3,282,566.

In the presently known, or so-called standard type, scissorstype liftinglinkage elevators of the prior art as shown, for example, by each of theforegoing patents the scissors lift arms are connected by pivot means onthe line of intersection formed by the straight plane between andthrough the center of rotation of the platform support and the center ofrotation of the base support of one arm and the straight plane betweenand through the center of rotation of the platform support and thecenter of rotation of the base support of the other arm, with the resultthat the lifting actuating load required at lift-off to raise thepivotally connected scissors arms and, of course, the platfonn, from thecollapsed package is much greater than the lifting actuating load duringthe remainder of the entire lifting cycle, that is, until the platformreaches its required height. Because of the required additional liftingload at liftoff'from the package, such prior art elevators includeauxiliary or secondary lifting actuators, in addition to their primarylifting actuator.

The scissors-type liftinglinkage elevator of this invention includes allthe conventional or known component elements, such as the movableplatform, the base member, a scissors linkage having pivotally connectedarms, with said arms having support means on the platform and the base,and actuating means for lifting, and of course lowering, the scissorslinkage and the platform. The foregoing problems, with particularemphasis on the development of the necessary actuating force toaccomplish the initial lift-off, are solved in the elevator of thisinvention simply and economically by utilizing in the elevatorstructure, in combination with the foregoingdescribed conventional orknown elements of the elevator, a pivot means for pivotally connectingthe scissors linkage is positioned offset below the general planes ofthe frames. The two arms forming each frame have pivot elements atopposite ends thereon and each plane just referred to passes through allfour pivots in each frame. An imaginary straight line connecting thepivots in each arm in one frame would pass through this plane. Thepivots just referred to connecting the two pairs of frames lie belowthese lines. A linear actuator comprising a hydraulic piston, piston rodand cylinder assembly is connected with one of the frames at a pointabove the general plane of this frame. This point of attachment islocated between the pivot between the frames and the load platform. Theother end of the linear actuator is pivoted near the base of one of theframes. As a result, we provide means to secure an almost constantlifting force during the entire lifting cycle and simultaneouscontrolled platform translation in the direction transverse to thelifting direction and an actuator load at initial vNo. 3,220,585 andClarke US. Pat. No.

, lift-off which is lower than the combined actuator loads of theprimary and auxiliary actuators as used in the foregoing described priorart elevators,

One of the objects of this invention is to provide an elevator such as,for example, a commercial aircraft cargo-loading elevator, wherein theactuator load or force has a minimum variation in lifting actuatingforce or, in other words, is as substantially constantas possible andthere is required a relatively lower actuator force or load without theneed for additional auxiliary or secondary actuator means at the initiallift-off, and there is attained simultaneous controlled platformtranslation in the direction transverse to the lifting direction, all ina simply and economically made lifting structure.

Other objects and features will be readily apparent from the followingdetailed description which is not limiting but only illustrative of thepreferred embodiment of this invention.

In the drawings FIG. 1 is a view in perspective of the elevator of thisinvention;

FIG. 2 is a diagrammatic view in perspective of the straightintersecting planes through component elements of the elevator shown inFIG. 1;

FIG.,3 is a diagrammatic showing of the elevator of FIG. 1 in variouspositions during the lifting cycle;

FIG. 4 is a graphical representation of actuator load in pounds versusplatform travel in feet during the lifting cycle of the elevator shownin FIG. I with relation back to the diagrammatic showing of the elevatorat various positions during the lifting cycle as shown in FIG. 3;

FIG. 5 shows a modification.

The scissors-type lifting linkage elevator I of this invention includesperipheral structural members 2, 4, 6 and 8 defining a generallyrectangular peripheral frame or base I0. Said base 10 is shown restingon the ground, but may include bracketmounted ground-engaging wheels(not shown) for supporting it and of course the elevator adjacent to theground for movement, as required. Cross braces I2 extend between sideframe members 4 and 8, and fixedly attached to said members 4 and 8, asby welding, are channel members or tracks 14 and I6.

Scissors linkage 18 has pivotally connected inner arm 20 and outer arm22. Outer arm 22 is pivotally connected to base I0 by pivot pins 24 andbrackets 26 attached to frame-bracing channel 28 fixedly secured to andbetween members 4 and 8. Outer arm 22 also carries on its free endrollers 30. Load-carrying platform 32 is supported by scissors linkagel8 and is connected to base I0 by scissors linkage 18, as is clearlyshown in the appended drawings. F ixedly attached to side members 34 and36 of platform 32, as by welding, are channel members or tracks 38 and40 for guiding rollers 30, 30 as they move therealong in the directionfrom rear member 42 of platform 32 toward front member 44 of platform 32during the lifting of platform 32 from the package or collapsed positionof the scissors linkage l8 and platform 32.

Vertically aligned, when the s'cissors linkage l8 and platform 32 are inpackage or collapsed position, with frame-bracing channel 28 isframe-bracing channel 46 fixedly secured to and between platform sidemembers 34 and 36. Platform 32 includes a generally rectangularly shapedperipheral frame of peripheral structural members 44, 34, 42 and 36having positioned thereon and joined thereto floor 48 having positionedtherein and thereon casters (not shown) for enabling the easy movementof a load. Inner arm 20 is pivotally connected to platform 32 by pivotpins 50 and brackets 52 attached to bracing channel 46. Inner arm 20also carries on its free end rollers 54 which are guided by channelmembers or tracks 14 and 16 as they move therealong in the directionfrom frame member 6 of base 10 toward frame member 2 of base 10 duringthe lifting cycle. When scissors linkage l8 and platform 32 and, ofcourse, base 10 are in package or collapsed position, pivot pins 24 and50, brackets 26 and 52, and rollers 30, 30 and 54, 54 are respectivelyin vertical alignment as are frame-bracing channels 28 and 46,

Inner arm 20 includes spaced-apart parallel members 56, 56. The upperopposite portions of said spaced-apart parallel members 56, 56 arebracedby X-brace 58, and the lower opposite portions of saidspaced-apart parallel members 56, 56 are braced by X-brace 60. Secured,as by welding, to crossstrut 62 of X-brace 58 and also secured, as bywelding, to cross-strut 64 of X-brace 60 is rectangularly shaped platebrace 66. Each of said members 56, 56 has, in its middle position, as anintegral part thereof, a trapezoidally shaped projection 68 extendingbelow a straight line drawn between the pivot elements at opposite endsof the arm with circular opening 70 therethrough. the centers of saidcircular openings 70, 70 being on the same centerline.

Outer arm 22 includes spaced-apart parallel members 72, 72. The upperopposite portions of said spaced-apart parallel members 72, 72 arebraced by K-brace 74, and the lower opposite portions of saidspaced-apart parallel members 72, 72 are braced by K-brace 76. Each ofsaid members 72, 72 has, in its middle portion, as an integral partthereof, a trapezoidally shaped projection 80 extending below thegeneral plane of the frame with circular opening 82, the centers of saidcircular openings 82, 82, 70, 70 being on the same centerline. The framecomposed of arms 22 will hereinafter be called the first frame and thathaving arms 20 as the first frame.

The outer surface 84 of each member 56 of inner arm 20 is spaced apartfrom the inner surface 86 of each member 72 of outer arm 22, and eachspace therebetween is wide enough to accommodate the greater portion ofa linear actuator such as one of the hydraulic rams 88 utilized forlifting platform 32 and, of course, scissors linkage 18 from package orcollapsed position.

The linear actuators preferably used to lift platform 32 and scissorslinkage 18 from package or collapsed position are hydraulic rams 88, 88each including a cylinder 90 and a piston 92, each piston 92 beingpivotally connected at its upper end to a shaft 94 fixedly secured inbrackets 96 secured, as by welding, to the outer surface 84 of member 56of inner arm 20. These brackets are offset above the general plane ofthe frame. These brackets can, of course, be side extensions of the armsshaped like the extensions 68 and 80 instead of separate elements weldedto the arms. Cylinder 90 of each hydraulic ram 88 is pivotally connectedat its lower end to a shaft 98 fixedly secured in a bracket 3 secured,as by welding, to crossbeam 5 secured to members 72, 72 at the innersurfaces 86, 86 thereof. This pivot 98 should not be higher than framepivot 24 and the greater the distance it lies below frame pivot 24 themore efiicient is the hydraulic ram at initial liftoff. Fluid underpressure is supplied to said hydraulic rams as required to lift platform32 and scissors linkage 18 by wellknown means such as, for example,electrical pump means (not shown) driven by an internal combustionengine (not shown) and suitable switch means (not shown) are used forcontrolling operation of said pump supplying said fluid to rams 88, 88so that lifting and lowering platform 32 and scissors linkage 18 may becontrolled both from the ground and from platform 32.

Positioned through and secured in circular openings 82 and 70 of one setof members 72, and 56, respectively, is shaft 7a, and positioned throughand secured in circular openings 82 and 70 of the other set of members72 and 56, respectively, is shaft 7b, the centers of said circularopenings 82, 82, 70, 70 being on the same centerline which coincideswith the centerline of said shafts 7a and 7b, said shafts 7a and 7blikewise being on the same centerline. Scissors arms 20 and 22 arepivoted to each other for movement with respect to each other on saidshafts 7a and 7b.

Referring to FIG. 2, therein is shown a diagrammatic perspective view ofthe straight intersecting planes A and B through inner arm 20 and outerarm 22, respectively, together with trapezoidally shaped projection 80having circular opening 82, the projection 80 and opening 82 being shownthereon for purposes of clarity only. Planes A and B are straight planesand the pivot elements 50-54 and -24 at opposite ends thereof lie insaid planes. Plane A is in the plane between and through the center ofrotation c of the platform support means or pivot pins and the center ofrotation d of the base support means or rollers 54 of inner arm 20. Thecenters of rotation of the pivot pins 50 coincide and are on line c,while the centers of rotation of the rollers 54 coincide and are on lined, and lines c and d are parallel to each other. Plane B is the planebetween and through the center of rotation a of the platform supportmeans or rollers 30 and the center of rotation b of the base supportmeans or pivot pins 24 of outer arm 22.

The centers of rotation of rollers 30 coincide and are on line a, whilethe centers of rotation of the pivot pins 24 coincide and are on line b,and lines a and b are parallel to each other. The line of intersectionof planes A and B is line G--G and is intermediate lines a and b andlines c and d. Line F-F is the centerline through the centers ofcircular openings 82, 82, 70, and is ofiset from line G-G, as is clearlyshown in the appended drawings. Line q of plate A is a straight linepassing through the centers of rotation of pivot point 50 and the roller54 of inner arm 20, and line r of plane A likewise is a straight linepassing through the centers of rotation of pivot point 50 and roller 54of inner arm 20. Thus it is readily apparent from the appended drawingsthat lines 0, q, d, r, form straight plane A. Line s of plane B is astraight line passing through the centers of rotation of roller 30 andpivot point 24 of outer arm 22, while line I of plane B likewise is astraight line passing through the center of rotation of roller 30 andthe center of rotation of pivot point 24 of outer arm 22. Thus it isreadily apparent from the appended drawings that lines a, s, b, 1 formstraight plane B. Extensions 81 on plane A have pivot openings B andthese pivot openings lie above the plane of A, above pivot 82 betweenthe planes, and between the latter pivot and pivot 50 at the top of theplane. The hydraulic rams are connected with these pivots.

Now referring to FIG. 3, therein is set forth a diagrammatic showing ofthe elevator of this invention in various positions during the entirelifting cycle, namely from the package or collapsed position to thefinal lift position at three points of said lifting cycle, namely point1, point 12 and point 3, the posi tions at points 2 and 3 being shown indotted lines. The point 1 position shows diagrammatically the scissorslift arms 20 and 22 in collapsed or packaged condition. The point 2position shows diagrammatically the scissors lift arms 20 and 22approximately midway during the lifting cycle. The point 3 positionshows diagrammatically the scissors lift arms 20 and 22 at the end ofthe lifting cycle. Line 2 designates outer scissors lift arm 22. Line fdesignates inner scissors lift arm 20. With reference back to elevator las shown in FIG. 1, pivot pins 24 and 50 and rollers 54 and 30 arediagrammatically shown by points in FIG. 3. Line g designates thecenterline through cylinder and piston 92 of each actuator or hydraulicram 88, the respective centerlines of said actuators being on the sameplane, as is clearly shown in the appended drawings. Point j designatesthe pivot point offset from center or. stated in other words, theintersecting line F-F (FIG. 2) offset from the intersecting line 6-0(FIG. 2) of the straight planes A and B through inner arm 20 and outerarm 22, respectively. Links k and (designate the connecting linesbetween pivoting pointj and the outer arm 22 and the inner arm 20,designated by lines e andf, respectively. Now, the moment arm D is aline segment drawn from pivot] to the line of actuation or centerline gmaking substantially a right angle with the centerline g. The linearactuator which performs the lifting is shown in FIG. 1 as beingpivotally connected at its upper end at 84 to a bracket or upwardextension of the frame 20 and the lower end to the base at a pointcoaxial with pivot 24 of frame 22. The arrangement can be reversed asshown in FIG. 5 so that the upper end of the actuator 90'-92' isconnected with an upward extension of frame 22 at 102', above the pivot82' for the frames, and the lower end to the frame 20' adjacent rollerpivot 54.

In either arrangement, the pivot axis between the frames is below thegeneral plane of the frame and the pivot for the upper end of theactuator is above the plane of frame 20 in the preferred arrangement ofFIG. 1 or above the plane of frame 22 just described. The distance ofone below and the other above can be about the same and this is themoment arm. The length of the frame is about 10 times the moment arm butit may be as low as seven and as high as 13.

The rollers at the outer ends of the frames travel over trackway areasalthough the areas are sometimes referred to herein as trackways per se.It is clear, however, that the horizontal web of each arm in the framepresents in effect the trackway, affording smooth passage for theserollers.

The presence of the moment arm D during the operation of elevator 1 ofthis invention makes possible the initial lift-off without the need forany auxiliary or secondary actuator means and without the need for anyadditional eccentric cam and roller means at an actuator load or forcerelatively lower than that previously utilized in prior art elevators,with the accompanying minimum variation in lifting actuator load orforce during the entire lifting cycle wherein the platform and scissorslinkage is raised vertically from the package or collapsed position withrespect to horizontal ground. Thus, there is here permitted a scissorslinkage geometry wherein the actuator means is pivotally connected toboth scissors lift arms and 22 and said actuator means is actually movedupwardly with the upward movement of the scissors linkage and platformand there is accomplished a controlled platform translation in thedirection X transverse to the upward lifting direction all with aminimum variation in lifting actuator load or force duiing the entirelifting cycle. in heretofore known elevators not utilizing the hereindescribed offset pivot means and not utilizing said ofi'set pivot meanstogether with the herein described actuator means pivotally connected tothe outer and inner scissors lift arms as herein described, such momentarm as herein shown and designated by perpendicular distance D has beenabsent during the entire lifting cycle making it necessary to use theaforementioned auxiliary or secondary actuator means or the eccentricand roller means to accomplish initial lift-off at an initial actuatorload at lift-off relatively higher than required with the elevator ofthis invention and with a great variation in lifting actuator forceduring the entire lifting cycle, all as clearly shown in the appendeddrawings with particular emphasis on FIGS. 3 and 4. FIG. 4 is agraphical representation of actuator load in pounds versus platformtravel in feet upwardly, of course, with respect to ground during thelifting cycle of the elevator of this invention. Line R is a plot of theactuator load versus upward platform travel of the three positions orpoints (points 1, 2 and 3) of the elevator during the lifting cycle, andline S is a plot of actuator load versus upward platform travel ofcomparable positions or points of the prior art elevators. As is readilyseen at 0 feet, or in package position, the actuator force required forinitial lift-off by the elevator of this invention is less than theactuator force required for initial lift-off by prior art elevators, andthis because of the presence of the moment arm D at initial lift-off aswell as during the entire lifting cycle. In the prior art elevatorstructures such a moment arm as is moment arm D is not present atinitial lift-off and thus there is required an actuator load at initiallift-off greater than the actuator loads during the upward travel of theplatform during the lifting cycle. At the position shown by point 1 themoment arm D in the elevator of this invention is greater than therespective moment arm D at the positions shown by points 2 and 3, andtherefore, the actuator force required is somewhat less. However, forall intents and purposes in this art the variation in lifting actuatorload or force is a minimum during the entire lifting cycle, and theactuator load is relatively constant during the entire lifting cycle ascompared to the actuator load in prior art elevators wherein a momentarm such as is moment arm D herein is absent at initial lift-off and themoment arms between the respective centerlines of the actuator means andthe respective scissors lift arm pivot points (said moment arms beingthrough the pivot point and perpendicular to said centerlines) regularlyincrease proportionately to the lifting distance, as shown by line S,during the entire lifting cycle. Further, in the elevator of thisinvention, moment arm D remains almost constant, as compared to theanalogous moment arms present in the elevators of the prior artelevators, as shown by the plots in FIG. 4 of the appended drawings.

With further reference to FIG. 3 curve M shows the path followed bypivot pins 50 during the upward travel of the scissors linkage and theplatform, and there results a movement of said platform in the directionof arrow X, pivot pins 50 being fixed with relation to platform 32.However, rollers 30 being movable with relation to platform 32, curve Nshows the path followed by rollers 30 during the upward travel of thescissors linkage and the platform.

W at IS claimed;

1. A cargo-loading elevator comprising a base, a load platform, ascissors linkage for raising the platform from a lowered to a raisedposition and including firstvand second frames which are pivotedtogether substantially midway between their ends to form said scissorslinkage, each frame including a pair of spaced arms wit bracesinterconnecting the arms of said pair, fixed pivots mounting one end ofthe first frame at a first end of the base, and fixed pivots mountingthe adjacent end of the second frame to the movable platform at saidfirst end, rollers pivoted at the opposite ends of said frames, andtrackways extending longitudinally of the base and platform at theopposite end of the elevator on which the rollers travel as the platformis raised and lowered, the arms in each frame having first offsetsections which are offset below the general plane of the frame, thepivots connecting said frames to form the scissors linkage passingthrough said offset portions below said planes, one of said frames alsohaving a second offset portion which is offset above the plane of saidframe at a point between said scissors linkage pivots and the platform,.a hydraulic piston, piston rod and cylinder assembly pivotallyconnected at one end thereof to said second offset portion lying abovesaid plane and at its other end to a point adjacent the base.

2. The structure defined in claim 2 wherein the frame having the secondoffset portion, to which one end of the hydraulic assembly is connected,is the second frame and the other end of the hydraulic assembly isconnected to the base by a fixed pivot which is adjacent the first framebase pivot.

3. The structure defined in claim 1 wherein the combined distance of thepivots below and above said general planes of the frames constitutes amoment arm and the length of each frame is between seven and thirteentimes the length of the moment arm.

4. The structure defined in claim 1 wherein the frames are provided withextensions below and above said general planes through which saidseveral pivots pass.

5. The structure defined in claim I wherein the frame having the secondextension, to which the hydraulic assembly is connected, is the firstframe.

N 2309 l0l0l5 I I I. I. I

1. A cargo-loading elevator comprising a base, a load platform, ascissors linkage for raising the platform from a lowered to a raisedposition and including first and second frames which are pivotedtogether substantially midway between their ends to form said scissorslinkage, each frame including a pair of spaced arms wit bracesinterconnecting The arms of said pair, fixed pivots mounting one end ofthe first frame at a first end of the base, and fixed pivots mountingthe adjacent end of the second frame to the movable platform at saidfirst end, rollers pivoted at the opposite ends of said frames, andtrackways extending longitudinally of the base and platform at theopposite end of the elevator on which the rollers travel as the platformis raised and lowered, the arms in each frame having first offsetsections which are offset below the general plane of the frame, thepivots connecting said frames to form the scissors linkage passingthrough said offset portions below said planes, one of said frames alsohaving a second offset portion which is offset above the plane of saidframe at a point between said scissors linkage pivots and the platform,a hydraulic piston, piston rod and cylinder assembly pivotally connectedat one end thereof to said second offset portion lying above said planeand at its other end to a point adjacent the base.
 2. The structuredefined in claim 2 wherein the frame having the second offset portion,to which one end of the hydraulic assembly is connected, is the secondframe and the other end of the hydraulic assembly is connected to thebase by a fixed pivot which is adjacent the first frame base pivot. 3.The structure defined in claim 1 wherein the combined distance of thepivots below and above said general planes of the frames constitutes amoment arm and the length of each frame is between seven and thirteentimes the length of the moment arm.
 4. The structure defined in claim 1wherein the frames are provided with extensions below and above saidgeneral planes through which said several pivots pass.
 5. The structuredefined in claim 1 wherein the frame having the second extension, towhich the hydraulic assembly is connected, is the first frame.